Ontario could be at risk of energy shortfalls this summer if heat waves continue to strike, according to a report by a North American electricity regulator.

The province is the only Canadian region listed in the May summer reliability assessment as being at an “elevated risk” of shortfalls should temperatures spike.

The report, released by non-profit North American Electric Reliability Corporation (NERC), suggests Ontario has entered a period in which “generation and transmission outages will be increasingly difficult to accommodate.”

The report noted planned outages due to nuclear plant refurbishment have reduced electricity supply resources. It also suggests the Windsor-Essex area may not be able to get “sufficient supply” due to increasing demand.

However, the regulator also says Ontario could rely on imports and outage management for a “significant number of weeks” under both normal and extreme weather conditions.

Tom Chapman, an energy economist with The Brattle Group, told CTV News Toronto on Monday the risk of an energy shortage is “slightly heightened” due to generated outages and potentially bad weather, however, he doesn’t anticipate mass power outages unless there are extreme circumstances.

“We will almost certainly be okay. There really is not any cause to be alarmed,” he said.

“It's the system operators doing their prudent planning and making sure they're putting everything in place to ensure that there isn't a localized grid outage.”

Chapman says Ontario has come a long way since the summer of 2003, when a massive power outage caused a blackout not only across the province, but also into the United States. He notes the province has boosted its supply of renewable, nuclear and hydro-electric power. He also said that if Ontario gets in a bind, it has more partnerships and can purchase power from neighbours to keep the lights on.

“We're in a much more robust situation that we were in 2003,” Chapman said. “We have more tools in the toolbox to deal with difficult circumstances than we did in the past.”

But the New Democratic Party MPP Peter Tabuns feels like funding cuts to renewable projects by the Progressive Conservative government are partially to blame for the summer assessment’s conclusions.

“Ontario is the only province in Canada that is rated with elevated risk that it can’t meet peak demand,” Tabuns said in the Legislature Thursday. “After five years, this government’s policies of cutting funding for efficiency and conservation, of demolishing wind farms and cancelling other renewable projects have led to this.

“We’re going to see more extreme weather that increases the chances that we’ll have outages.”

Minister of Energy Todd Smith responded by saying the province’s system is 90 per cent clean and “attracting investment from all around the world.”

“We have a grid in Ontario that is the envy of all jurisdictions in North America: one that’s clean, one that’s affordable, one that’s reliable and one that’s safe.”

The report notes that an ongoing transmission outage at the interconnection between New York and St. Lawrence could impact the province’s ability to important and export energy. But this issue is expected to be resolved by the end of the year.

Much of southern and central Ontario experienced a multi-day heat event last week, with temperatures soaring to about 31 C before humidex.

With files from CTV News Toronto's Queen's Park Bureau Chief Siobhan Morris